提问人：M. Beausoleil 提问时间：8/5/2023 最后编辑：ThomasIsCodingM. Beausoleil 更新时间：8/5/2023 访问量：29
创建一个数据框，其中包含 2 个变量的成对比较，其中顺序在 R 中无关紧要
Create a data frame with pairwise comparisons of 2 variables where order don't matter in R
问：
我有变量，我想进行所有成对比较，但删除比较相等的行（例如，“A”==“A”），并且只保留一个只有顺序变化的比较，所以保持“A”与“B”或“B”与“A”。
我有这个代码在R中执行此操作：
sp.all.var = c(LETTERS[1:10])
length(sp.all.var)^2
df.pairwise = expand.grid(sp.all.var,sp.all.var)
nrow(df.pairwise)
df.pairwise.sub1 = df.pairwise[df.pairwise$Var1!=df.pairwise$Var2,]
df.pairwise.sub1$compare = apply(df.pairwise.sub1, 1, function(x) paste(sort(x), collapse = "-"))
nrow(df.pairwise.sub1)
df.pairwise.sub2 = df.pairwise.sub1[!duplicated(df.pairwise.sub1$compare), ]
nrow(df.pairwise.sub2)
我想知道是否有一种方法可以以更简单的方式做到这一点（是否有内置功能可以做到这一点？是否有软件包？
答：
2赞
jblood94
8/5/2023
#1
你可能想要.combn
combn(LETTERS[1:10], 2, paste, collapse = "-")
#> [1] "A-B" "A-C" "A-D" "A-E" "A-F" "A-G" "A-H" "A-I" "A-J" "B-C" "B-D" "B-E"
#> [13] "B-F" "B-G" "B-H" "B-I" "B-J" "C-D" "C-E" "C-F" "C-G" "C-H" "C-I" "C-J"
#> [25] "D-E" "D-F" "D-G" "D-H" "D-I" "D-J" "E-F" "E-G" "E-H" "E-I" "E-J" "F-G"
#> [37] "F-H" "F-I" "F-J" "G-H" "G-I" "G-J" "H-I" "H-J" "I-J"
或者作为：data.frame
as.data.frame(t(combn(LETTERS[1:10], 2, \(x) c(x, paste(x, collapse = "-")))))
#> V1 V2 V3
#> 1 A B A-B
#> 2 A C A-C
#> 3 A D A-D
#> 4 A E A-E
#> 5 A F A-F
#> 6 A G A-G
#> 7 A H A-H
#> 8 A I A-I
#> 9 A J A-J
#> 10 B C B-C
#> 11 B D B-D
#> 12 B E B-E
#> 13 B F B-F
#> 14 B G B-G
#> 15 B H B-H
#> 16 B I B-I
#> 17 B J B-J
#> 18 C D C-D
#> 19 C E C-E
#> 20 C F C-F
#> 21 C G C-G
#> 22 C H C-H
#> 23 C I C-I
#> 24 C J C-J
#> 25 D E D-E
#> 26 D F D-F
#> 27 D G D-G
#> 28 D H D-H
#> 29 D I D-I
#> 30 D J D-J
#> 31 E F E-F
#> 32 E G E-G
#> 33 E H E-H
#> 34 E I E-I
#> 35 E J E-J
#> 36 F G F-G
#> 37 F H F-H
#> 38 F I F-I
#> 39 F J F-J
#> 40 G H G-H
#> 41 G I G-I
#> 42 G J G-J
#> 43 H I H-I
#> 44 H J H-J
#> 45 I J I-J
1赞
ThomasIsCoding
8/5/2023
#2
你也可以用rep + sequence
x <- LETTERS[1:10]
paste0(
rep(x, (length(x) - 1):0), "-",
x[sequence((length(x) - 1):0, from = 2:length(x))]
)
这给了
[1] "A-B" "A-C" "A-D" "A-E" "A-F" "A-G" "A-H" "A-I" "A-J" "B-C" "B-D" "B-E"
[13] "B-F" "B-G" "B-H" "B-I" "B-J" "C-D" "C-E" "C-F" "C-G" "C-H" "C-I" "C-J"
[25] "D-E" "D-F" "D-G" "D-H" "D-I" "D-J" "E-F" "E-G" "E-H" "E-I" "E-J" "F-G"
[37] "F-H" "F-I" "F-J" "G-H" "G-I" "G-J" "H-I" "H-J" "I-J"
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